Lenses capable of post-fabrication power modification

ABSTRACT

The present invention relates to lenses that are capable of post-fabrication power modifications. In general, the inventive lenses comprise (i) a first polymer matrix and (ii) a refraction modulating composition that is capable of stimulus-induced polymerization dispersed therein. When at least a portion of the lens is exposed to an appropriate stimulus, the refraction modulating composition forms a second polymer matrix. The amount and location of the second polymer matrix may modify a lens characteristic such as lens power by changing its refractive index and/or by altering its shape. The inventive lenses have a number of applications in the electronics and medical fields as data storage means and as medical lenses, particularly intraocular lenses, respectively.

RELATED APPLICATIONS

[0001] This application is a continuation of and claims priority of U.S.application Ser. No. 09/416,044, filed Oct. 8, 1999, which claimspriority of U.S. Provisional Application No. 60/115,617, filed Jan. 12,1999; claims priority of U.S. Provisional Application No. 60/132,871,filed May 5, 1999; and claims priority of U.S. Provisional ApplicationNo. 60/140,298, filed Jun. 17, 1999; and which is fully incorporatedherein by reference.

BACKGROUND

[0002] Approximately two million cataract surgery procedures areperformed in the United States annually. The procedure generallyinvolves making an incision in the anterior lens capsule to remove thecataractous crystalline lens and implanting an intraocular lens in itsplace. The power of the implanted lens is selected (based uponpre-operative measurements of ocular length and corneal curvature) toenable the patient to see without additional corrective measures (e.g.,glasses or contact lenses). Unfortunately, due to errors in measurement,and/or variable lens positioning and wound healing, about half of allpatients undergoing this procedure will not enjoy optimal vision withoutcorrection after surgery. Brandser et al., Acta Ophthalmol Scand75:162-165 (1997); Oshika et al., J cataract Refract Surg 24:509-514(1998). Because the power of prior art intraocular lenses generallycannot be adjusted once they have been implanted, the patient typicallymust choose between replacing the implanted lens with another lens of adifferent power or be resigned to the use of additional correctivelenses such as glasses or contact lenses. Since the benefits typicallydo not outweigh the risks of the former, it is almost never done.

[0003] An intraocular lens whose power may be adjusted afterimplantation and subsequent wound healing would be an ideal solution topost-operative refractive errors associated with cataract surgery.Moreover, such a lens would have wider applications and may be used tocorrect more typical conditions such as myopia, hyperopia, andastigmatism. Although surgical procedures such as LASIK which uses alaser to reshape the cornea are available, only low to moderate myopiaand hyperopia may be readily treated. In contrast, an intraocular lens,which would function just like glasses or contact lenses to correct forthe refractive error of the natural eye, could be implanted in the eyeof any patient. Because the power of the implanted lens may be adjusted,post-operative refractive errors due to measurement irregularitiesand/or variable lens positioning and wound healing may be fine tunedin-situ.

SUMMARY

[0004] The present invention relates to optical elements, particularlymedical lenses and methods of using the same. In general, the inventivelens comprises (i) a first polymer matrix and (ii) a refractionmodulating composition that is capable of stimulus-inducedpolymerization dispersed therein. In one embodiment, when at least aportion of the lens is exposed to an appropriate stimulus, therefraction modulating composition forms a second polymer matrix, theformation of which modifies lens power.

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0005]FIG. 1 is a schematic of a lens of the present invention beingirradiated in the center followed by irradiation of the entire lens to“lock in” the modified lens power.

[0006]FIG. 2 illustrates the prism irradiation procedure that is used toquantify the refractive index changes after being exposed to variousamounts of irradiation.

[0007]FIG. 3 shows unfiltered moiré fringe patterns of an inventive IOL.The angle between the two Ronchi rulings was set at 12° and thedisplacement distance between the first and second moiré patterns was4.92 mm.

[0008]FIG. 4 is a Ronchigram of an inventive IOL. The Ronchi patterncorresponds to a 2.6 mm central region of the lens.

[0009]FIG. 5 is a schematic illustrating a second mechanism whereby theformation of the second polymer matrix modulates a lens property byaltering lens shape.

[0010]FIG. 6 are Ronchi interferograms of an IOL before and after lasertreatment depicting approximately a +8.6 diopter change in lens powerwithin the eye. The spacing of alternative light and dark bands isproportional to lens power.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention relates to optical elements (e.g., lensesand prisms) that are capable of post-fabrication power modifications.More particularly, the present invention relates to intraocular lenseswhose power may be adjusted in-situ after implantation in the eye.

[0012] The inventive optical elements comprise a first polymer matrixand a refraction modulating composition dispersed therein. The firstpolymer matrix forms the optical element framework and is generallyresponsible for many of its material properties. The refractionmodulating composition (“RMC”) may be a single compound or a combinationof compounds that is capable of stimulus-induced polymerization,preferably photo-polymerization. As used herein, the term“polymerization” refers to a reaction wherein at least one of thecomponents of the refraction modulating composition reacts to form atleast one covalent or physical bond with either a like component or witha different component. The identities of the first polymer matrix andthe refraction modulating compositions will depend on the end use of theoptical element. However, as a general rule, the first polymer matrixand the refraction modulating composition are selected such that thecomponents that comprise the refraction modulating composition arecapable of diffusion within the first polymer matrix. Put another way, aloose first polymer matrix will tend to be paired with larger RMCcomponents and a tight first polymer matrix will tend to be paired withsmaller RMC components.

[0013] Upon exposure to an appropriate energy source (e.g., heat orlight), the refraction modulating composition typically forms a secondpolymer matrix in the exposed region of the optical element. Thepresence of the second polymer matrix changes the materialcharacteristics of this portion of the optical element to modulate itsrefraction capabilities. In general, the formation of the second polymermatrix typically increases the refractive index of the affected portionof the optical element. After exposure, the refraction modulatingcomposition in the unexposed region will migrate into the exposed regionover time. The amount of RMC migration into the exposed region is timedependent and may be precisely controlled. If enough time is permitted,the RMC components will re-equilibrate and redistribute throughoutoptical element (i.e., the first polymer matrix, including the exposedregion). When the region is re-exposed to the energy source, therefraction modulating composition (“RMC”) that has since migrated intothe region (which may be less than if the RMC composition were allowedto re-equilibrate) polymerizes to further increase the formation of thesecond polymer matrix. This process (exposure followed by an appropriatetime interval to allow for diffusion) may be repeated until the exposedregion of the optical element has reached the desired property (e.g.,power, refractive index, or shape). At this point, the entire opticalelement is exposed to the energy source to “lock-in” the desired lensproperty by polymerizing the remaining RMC components that are outsidethe exposed region before the components can migrate into the exposedregion. In other words, because freely diffusable RMC components are nolonger available, subsequent exposure of the optical element to anenergy source cannot further change its power. FIG. 1 illustrates oneinventive embodiment, refractive index modulation (thus lens powermodulation) followed by a lock in.

[0014] The first polymer matrix is a covalently or physically linkedstructure that functions as an optical element and is formed from afirst polymer matrix composition (“FPMC”).

[0015] In general, the first polymer matrix composition comprises one ormore monomers that upon polymerization will form the first polymermatrix. The first polymer matrix composition optionally may include anynumber of formulation auxiliaries that modulate the polymerizationreaction or improve any property of the optical element. Illustrativeexamples of suitable FPMC monomers include acrylics, methacrylates,phosphazenes, siloxanes, vinyls, homopolymers and copolymers thereof. Asused herein, a “monomer” refers to any unit (which may itself either bea homopolymer or copolymer) which may be linked together to form apolymer containing repeating units of the same. If the FPMC monomer is acopolymer, it may be comprised of the same type of monomers (e.g., twodifferent siloxanes) or it may be comprised of different types ofmonomers (e.g., a siloxane and an acrylic).

[0016] In one embodiment, the one or more monomers that form the firstpolymer matrix are polymerized and cross-linked in the presence of therefraction modulating composition. In another embodiment, polymericstarting material that forms the first polymer matrix is cross-linked inthe presence of the refraction modulating composition. Under eitherscenario, the RMC components must be compatible with and not appreciablyinterfere with the formation of the first polymer matrix. Similarly, theformation of the second polymer matrix should also be compatible withthe existing first polymer matrix. Put another way, the first polymermatrix and the second polymer matrix should not phase separate and lighttransmission by the optical element should be unaffected.

[0017] As described previously, the refraction modulating compositionmay be a single component or multiple components so long as: (i) it iscompatible with the formation of the first polymer matrix; (ii) itremains capable of stimulus-induced polymerization after the formationof the first polymer matrix; and (iii) it is freely diffusable withinthe first polymer matrix. In preferred embodiments, the stimulus-inducedpolymerization is photo-induced polymerization.

[0018] The inventive optical elements have numerous applications in theelectronics and data storage industries. Another application for thepresent invention is as medical lenses, particularly as intraocularlenses.

[0019] In general, there are two types of intraocular lenses (“IOLs”).The first type of an intraocular lens replaces the eye's natural lens.The most common reason for such a procedure is cataracts. The secondtype of intraocular lens supplements the existing lens and functions asa permanent corrective lens. This type of lens (sometimes referred to asa phakic intraocular lens) is implanted in the anterior or posteriorchamber to correct any refractive errors of the eye. In theory, thepower for either type of intraocular lenses required for emmetropia(i.e., perfect focus on the retina from light at infinity) can beprecisely calculated. However, in practice, due to errors in measurementof corneal curvature, and/or variable lens positioning and woundhealing, it is estimated that only about half of all patients undergoingIOL implantation will enjoy the best possible vision without the needfor additional correction after surgery. Because prior art IOLs aregenerally incapable of post-surgical power modification, the remainingpatients must resort to other types of vision correction such asexternal lenses (e.g., glasses or contact lenses) or cornea surgery. Theneed for these types of additional corrective measures is obviated withthe use of the intraocular lenses of the present invention.

[0020] The inventive intraocular lens comprises a first polymer matrixand a refraction modulating composition dispersed therein. The firstpolymer matrix and the refraction modulating composition are asdescribed above with the additional requirement that the resulting lensbe biocompatible.

[0021] Illustrative examples of a suitable first polymer matrix include:poly-acrylates such as poly-alkyl acrylates and poly-hydroxyalkylacrylates; poly-methacrylates such as poly-methyl methacrylate (“PMMA”),poly-hydroxyethyl methacrylate (“PHEMA”), and poly-hydroxypropylmethacrylate (“HPMA”); poly-vinyls such as poly-styrene andpoly-vinylpyrrolidone (“PNVP”); poly-siloxanes such aspoly-dimethylsiloxane; poly-phosphazenes, and copolymers of thereof.U.S. Pat. No. 4,260,725 and patents and references cited therein (whichare all incorporated herein by reference) provide more specific examplesof suitable polymers that may be used to form the first polymer matrix.In preferred embodiments, the first polymer matrix generally possesses arelatively low glass transition temperature (“T_(g)”) such that theresulting IOL tends to exhibit fluid-like and/or elastomeric behavior,and is typically formed by crosslinking one or more polymeric startingmaterials wherein each polymeric starting material includes at least onecrosslinkable group. Illustrative examples of suitable crosslinkablegroups include but are not limited to hydride, acetoxy, alkoxy, amino,anhydride, aryloxy, carboxy, enoxy, epoxy, halide, isocyano, olefinic,and oxime. In more preferred embodiments, each polymeric startingmaterial includes terminal monomers (also referred to as endcaps) thatare either the same or different from the one or more monomers thatcomprise the polymeric starting material but include at least onecrosslinkable group. In other words, the terminal monomers begin and endthe polymeric starting material and include at least one crosslinkablegroup as part of its structure. Although it is not necessary for thepractice of the present invention, the mechanism for crosslinking thepolymeric starting material preferably is different than the mechanismfor the stimulus-induced polymerization of the components that comprisethe refraction modulating composition. For example, if the refractionmodulating composition is polymerized by photo-induced polymerization,then it is preferred that the polymeric starting materials havecrosslinkable groups that are polymerized by any mechanism other thanphoto-induced polymerization.

[0022] An especially preferred class of polymeric starting materials forthe formation of the first polymer matrix is poly-siloxanes (also knownas “silicones”) endcapped with a terminal monomer which includes acrosslinkable group selected from the group consisting of acetoxy,amino, alkoxy, halide, hydroxy, and mercapto. Because silicone IOLs tendto be flexible and foldable, generally smaller incisions may be usedduring the IOL implantation procedure. An example of an especiallypreferred polymeric starting material isbis(diacetoxymethylsilyl)-polydimethylsiloxane (which ispoly-dimethylsiloxane that is endcapped with a diacetoxymethylsilylterminal monomer).

[0023] The refraction modulating composition that is used in fabricatingIOLs is as described above except that it has the additional requirementof biocompatibility.

[0024] The refraction modulating composition is capable ofstimulus-induced polymerization and may be a single component ormultiple components so long as: (i) it is compatible with the formationof the first polymer matrix; (ii) it remains capable of stimulus-inducedpolymerization after the formation of the first polymer matrix; and(iii) it is freely diffusable within the first polymer matrix. Ingeneral, the same type of monomers that is used to form the firstpolymer matrix may be used as a component of the refraction modulatingcomposition. However, because of the requirement that the RMC monomersmust be diffusable within the first polymer matrix, the RMC monomersgenerally tend to be smaller (i.e., have lower molecular weights) thanthe monomers which form the first polymer matrix. In addition to the oneor more monomers, the refraction modulating composition may includeother components such as initiators and sensitizers that facilitate theformation of the second polymer matrix.

[0025] In preferred embodiments, the stimulus-induced polymerization isphoto-polymerization. In other words, the one or more monomers thatcomprise the refraction modulating composition each preferably includesat least one group that is capable of photopolymerization. Illustrativeexamples of such photopolymerizable groups include but are not limitedto acrylate, allyloxy, cinnamoyl, methacrylate, stibenyl, and vinyl. Inmore preferred embodiments, the refraction modulating compositionincludes a photoinitiator (any compound used to generate free radicals)either alone or in the presence of a sensitizer. Examples of suitablephotoinitiators include acetophenones (e.g., α-substitutedhaloacetophenones, and diethoxyacetophenone);2,4-dichloromethyl-1,3,5-triazines; benzoin methyl ether; and o-benzoyloximino ketone. Examples of suitable sensitizers includep-(dialkylamino)aryl aldehyde; N-alkylindolylidene; andbis[p-(dialkylamino)benzylidene]ketone.

[0026] Because of the preference for flexible and foldable IOLs, anespecially preferred class of RMC monomers is poly-siloxanes endcappedwith a terminal siloxane moiety that includes a photopolymerizablegroup. An illustrative representation of such a monomer is

X—Y—X¹

[0027] wherein Y is a siloxane which may be a monomer, a homopolymer ora copolymer formed from any number of siloxane units, and X and X¹ maybe the same or different and are each independently a terminal siloxanemoiety that includes a photopolymerizable group. An illustrative exampleof Y include

[0028] wherein:

[0029] m and n are independently each an integer and

[0030] R¹, R², R³, and R⁴ are independently each hydrogen, alkyl(primary, secondary, tertiary, cyclo), aryl, or heteroaryl. In preferredembodiments, R¹, R², R³, and R⁴ is a C₁-C₁₀ alkyl or phenyl. Because RMCmonomers with a relatively high aryl content have been found to producelarger changes in the refractive index of the inventive lens, it isgenerally preferred that at least one of R¹, R², R³, and R⁴ is an aryl,particularly phenyl. In more preferred embodiments, R¹, R², and R³ arethe same and are methyl, ethyl or propyl and R⁴ is phenyl.

[0031] Illustrative examples of X and X¹ (or X¹ and X depending on howthe RMC polymer is depicted) are

[0032] respectively wherein:

[0033] R⁵ and R⁶ are independently each hydrogen, alkyl, aryl, orheteroaryl; and

[0034] Z is a photopolymerizable group.

[0035] In preferred embodiments, R⁵ and R⁶ are independently each aC₁-C₁₀ alkyl or phenyl and Z is a photopolymerizable group that includesa moiety selected from the group consisting of acrylate, allyloxy,cinnamoyl, methacrylate, stibenyl, and vinyl. In more preferredembodiments, R⁵ and R⁶ is methyl, ethyl, or propyl and Z is aphotopolymerizable group that includes an acrylate or methacrylatemoiety.

[0036] In especially preferred embodiments, an RMC monomer is of thefollowing formula

[0037] wherein X and X¹ are the same and R¹, R², R³, and R⁴ are asdefined previously. Illustrative examples of such RMC monomers includedimethylsiloxane-diphenylsiloxane copolymer endcapped with a vinyldimethylsilane group; dimethylsiloxane-methylphenylsiloxane copolymerendcapped with a methacryloxypropyl dimethylsilane group; anddimethylsiloxane endcapped with a methacryloxypropyldimethylsilanegroup.

[0038] Although any suitable method may be used, a ring-opening reactionof one or more cyclic siloxanes in the presence of triflic acid has beenfound to be a particularly efficient method of making one class ofinventive RMC monomers. Briefly, the method comprises contacting acyclic siloxane with a compound of the formula

[0039] in the presence of triflic acid wherein R⁵, R⁶, and Z are asdefined previously. The cyclic siloxane may be a cyclic siloxanemonomer, homopolymer, or copolymer. Alternatively, more than one cyclicsiloxane may be used. For example, a cyclic dimethylsiloxane tetramerand a cyclic methyl-phenylsiloxane trimer are contacted withbis-methacryloxypropyltetramethyldisiloxane in the presence of triflicacid to form a dimethyl-siloxane methyl-phenylsiloxane copolymer that isendcapped with a methacryloxylpropyl-dimethylsilane group, an especiallypreferred RMC monomer.

[0040] The inventive IOLs may be fabricated with any suitable methodthat results in a first polymer matrix with one or more components whichcomprise the refraction modulating composition dispersed therein, andwherein the refraction modulating composition is capable ofstimulus-induced polymerization to form a second polymer matrix. Ingeneral, the method for making an inventive IOL is the same as that formaking an inventive optical element. In one embodiment, the methodcomprises

[0041] mixing a first polymer matrix composition with a refractionmodulating composition to form a reaction mixture;

[0042] placing the reaction mixture into a mold;

[0043] polymerizing the first polymer matrix composition to form saidoptical element; and,

[0044] removing the optical element from the mold.

[0045] The type of mold that is used will depend on the optical elementbeing made. For example, if the optical element is a prism, then a moldin the shape of a prism is used. Similarly, if the optical element is anintraocular lens, then an intraocular lens mold is used and so forth. Asdescribed previously, the first polymer matrix composition comprises oneor more monomers for forming the first polymer matrix and optionallyincludes any number of formulation auxiliaries that either modulate thepolymerization reaction or improve any property (whether or not relatedto the optical characteristic) of the optical element. Similarly, therefraction modulating composition comprises one or more components thattogether are capable of stimulus-induced polymerization to form thesecond polymer matrix. Because flexible and foldable intraocular lensesgenerally permit smaller incisions, it is preferred that both the firstpolymer matrix composition and the refraction modulating compositioninclude one or more silicone-based or low T_(g) acrylic monomers whenthe inventive method is used to make IOLs.

[0046] A key advantage of the intraocular lens of the present inventionis that an IOL property may be modified after implantation within theeye. For example, any errors in the power calculation due to imperfectcorneal measurements and/or variable lens positioning and wound healingmay be modified in a post surgical outpatient procedure.

[0047] In addition to the change in the IOL refractive index, thestimulus-induced formation of the second polymer matrix has been foundto affect the IOL power by altering the lens curvature in a predictablemanner. As a result, both mechanisms may be exploited to modulate an IOLproperty, such as power, after it has been implanted within the eye. Ingeneral, the method for implementing an inventive IOL having a firstpolymer matrix and a refraction modulating composition dispersedtherein, comprises:

[0048] (a) exposing at least a portion of the lens to a stimulus wherebythe stimulus induces the polymerization of the refraction modulatingcomposition.

[0049] If after implantation and wound healing, no IOL property needs tobe modified, then the exposed portion is the entire lens. The exposureof the entire lens will lock in the then-existing properties of theimplanted lens.

[0050] However, if a lens characteristic such as its power needs to bemodified, then only a portion of the lens (something less than theentire lens) would be exposed. In one embodiment, the method ofimplementing the inventive IOL further comprises:

[0051] (b) waiting an interval of time; and

[0052] (c) re-exposing the portion of the lens to the stimulus.

[0053] This procedure generally will induce the further polymerizationof the refraction modulating composition within the exposed lensportion. Steps (b) and (c) may be repeated any number of times until theintraocular lens (or optical element) has reached the desired lenscharacteristic. At this point, the method may further include the stepof exposing the entire lens to the stimulus to lock-in the desired lensproperty.

[0054] In another embodiment wherein a lens property needs to bemodified, a method for implementing an inventive IOL comprises:

[0055] (a) exposing a first portion of the lens to a stimulus wherebythe stimulus induces the polymerization of the refraction modulatingcomposition; and

[0056] (b) exposing a second portion of the lens to the stimulus.

[0057] The first lens portion and the second lens portion representdifferent regions of the lens although they may overlap. Optionally, themethod may include an interval of time between the exposures of thefirst lens portion and the second lens portion. In addition, the methodmay further comprise re-exposing the first lens portion and/or thesecond lens portion any number of times (with or without an interval oftime between exposures) or may further comprise exposing additionalportions of the lens (e.g., a third lens portion, a fourth lens portion,etc.). Once the desired property has been reached, then the method mayfurther include the step of exposing the entire lens to the stimulus tolock-in the desired lens property.

[0058] In general, the location of the one or more exposed portions willvary depending on the type of refractive error being corrected. Forexample, in one embodiment, the exposed portion of the IOL is theoptical zone which is the center region of the lens (e.g., between about4 mm and about 5 mm in diameter). Alternatively, the one or more exposedlens portions may be along IOL's outer rim or along a particularmeridian. In preferred embodiments, the stimulus is light. In morepreferred embodiments, the light is from a laser source.

[0059]

[0060] In summary, the present invention relates to a novel opticalelement that comprises (i) a first polymer matrix and (ii) a refractionmodulating composition that is capable of stimulus-inducedpolymerization dispersed therein. When at least a portion of the opticalelement is exposed to an appropriate stimulus, the refraction modulatingcomposition forms a second polymer matrix. The amount and location ofthe second polymer matrix modifies a property such as the power of theoptical element by changing its refractive index and/or by altering itsshape.

EXAMPLE 1

[0061] Materials comprising various amounts of (a) poly-dimethylsiloxaneendcapped with diacetoxymethylsilane (“PDMS”) (36000 g/mol), (b)dimethylsiloxane-diphenylsiloxane copolymer endcapped withvinyl-dimethyl silane (“DMDPS”) (15,500 g/mol), and (c) aUV-photoinitiator, 2,2-dimethoxy-2-phenylacetophenone (“DMPA”) as shownby Table 1 were made and tested. PDMS is the monomer which forms firstpolymer matrix, and DMDPS and DMPA together comprise the refractionmodulating composition. TABLE 1 PDMS (wt. %) DMDPS (wt. %) DMPA (wt.%)^(a) 1 90 10 1.5 2 80 20 1.5 3 75 25 1.5 4 70 30 1.5

[0062] Briefly, appropriate amounts of PMDS (Gelest DMS-D33; 36000g/mol), DMDPS (Gelest PDV-0325; 3.0-3.5 mole % diphenyl, 15,500 g/mol),and DMPA (Acros; 1.5 wt % respect to DMDPS) were weighed together in analuminum pan, manually mixed at room temperature until the DMPAdissolved, and degassed under pressure (5 mtorr) for 2-4 minutes toremove air bubbles. Photosensitive prisms were fabricated by pouring theresulting silicone composition into a mold made of three glass slidesheld together by scotch tape in the form of a prism and sealed at oneend with silicone caulk. The prisms are ˜5 cm long and the dimensions ofthe three sides are ˜8 mm each. The PDMS in the prisms was moisturecured and stored in the dark at room temperature for a period of 7 daysto ensure that the resulting first polymer matrix was non-tacky, clear,and transparent.

[0063] The amount of photoinitiator (1.5 wt. %) was based on priorexperiments with fixed RMC monomer content of 25% in which thephotoinitiator content was varied. Maximal refractive index modulationwas observed for compositions containing 1.5% and 2 wt. % photoinitiatorwhile saturation in refractive index occurred at 5 wt. %.

EXAMPLE 2

[0064] Synthesis RMC Monomers

[0065] As illustrated by Scheme 1, commercially available cyclicdimethylsiloxane tetramer (“D₄”) cyclic methylphenylsiloxane trimer(“D₃′”) in various ratios were ring-opened by triflic acid andbis-methacryloxylpropyltetramethyldisiloxane (“MPS”) were reacted in aone pot synthesis. U.S. Pat. No. 4,260,725; Kunzler, J. F., Trends inPolymer Science, 4: 52-59 (1996); Kunzler et al. J. Appl. Poly. Sci.,55: 611-619 (1995); and Lai et al., J. Poly. Sci. A. Poly. Chem., 33:1773-1782 (1995).

[0066] Briefly, appropriate amounts of MPS, D₄, and D₃′ were stirred ina vial for 1.5-2 hours. An appropriate amount of triflic acid was addedand the resulting mixture was stirred for another 20 hours at roomtemperature. The reaction mixture was diluted with hexane, neutralized(the acid) by the addition of sodium bicarbonate, and dried by theaddition of anhydrous sodium sulfate. After filtration androtovaporation of hexane, the RMC monomer was purified by furtherfiltration through an activated carbon column. The RMC monomer was driedat 5 mtorr of pressure between 70-80° C. for 12-18 hours.

[0067] The amounts of phenyl, methyl, and endgroup incorporation werecalculated from ¹H-NMR spectra that were run in deuterated chloroformwithout internal standard tetramethylsilane (“TMS”). Illustrativeexamples of chemical shifts for some of the synthesized RMC monomersfollows. A 1000 g/mole RMC monomer containing 5.58 mole % phenyl (madeby reacting: 4.85 g (12.5 mmole) of MPS; 1.68 g (4.1 mmole) of D₃′; 5.98g (20.2 mmole) of D₄; and 108 μl (1.21 mmole) of triflic acid:δ=7.56-7.57 ppm (m, 2H) aromatic, δ=7.32-7.33 ppm (m, 3H) aromatic,δ=6.09 ppm (d, 2H) olefinic, δ=5.53 ppm (d, 2H) olefinic, δ=4.07-4.10ppm (t, 4H) —O—CH ₂CH₂CH₂—, δ=1.93 ppm (s, 6H) methyl of methacrylate,δ=1.65-1.71 ppm (m, 4H) —O—CH₂CH ₂CH₂—, δ=0.54-0.58 ppm (m, 4H)—O—CH₂CH₂CH ₂—Si, δ=0.29-0.30 ppm (d, 3H), CH ₃—Si-Phenyl, δ=0.04-0.08ppm (s, 50H) (CH ₃)₂Si of the backbone.

[0068] A 2000 g/mole RMC monomer containing 5.26 mole % phenyl (made byreacting: 2.32 g (6.0 mmole) of MPS; 1.94 g (4.7 mmole) of D₃′; 7.74 g(26.1 mmole) of D₄; and 136 μl (1.54 mmole) of triflic acid: δ=7.54-7.58ppm (m, 4H) aromatic, δ=7.32-7.34 ppm (m, 6H) aromatic, δ=6.09 ppm (d,2H) olefinic, δ=5.53 ppm (d, 2H) olefinic, δ=4.08-4.11 ppm (t, 4H) —O—CH₂CH₂CH₂—, δ=1.94 ppm (s, 6H) methyl of methacrylate, δ=1.67-1.71 ppm (m,4H) —O—CH₂CH ₂CH₂—, δ=0.54-0.59 ppm (m, 4H) —O—CH₂CH₂CH ₂—Si,δ=0.29-0.31 ppm (m, 6H), CH ₃—Si-Phenyl, δ=0.04-0.09 ppm (s, 112H) (CH₃)₂Si of the backbone.

[0069] A 4000 g/mole RMC monomer containing 4.16 mole % phenyl (made byreacting: 1.06 g (2.74 mmole) of MPS; 1.67 g (4.1 mmole) of D₃′; 9.28 g(31.3 mmole) of D₄; and 157 μl (1.77 mmole) of triflic acid: δ=7.57-7.60ppm (m, 8H) aromatic, δ=7.32-7.34 ppm (m, 12H) aromatic, δ=6.10 ppm (d,2H) olefinic, δ=5.54 ppm (d, 2H) olefinic, δ=4.08-4.12 ppm (t, 4H) —O—CH₂CH₂CH₂—, δ=1.94 ppm (s, 6H) methyl of methacrylate, δ=1.65-1.74 ppm (m,4H) —O—CH₂CH ₂CH₂—, δ=0.55-0.59 ppm (m, 4H) —O—CH₂CH₂CH ₂—Si, δ=0.31 ppm(m, 11H), CH ₃—Si-Phenyl, δ=0.07-0.09 ppm (s, 272H) (CH ₃)₂Si of thebackbone.

[0070] Similarly, to synthesize dimethylsiloxane polymer without anymethylphenylsiloxane units and endcapped with methyacryloxypropyldimethylsilane, the ratio of D₄ to MPS was varied without incorporatingD′₃.

[0071] Molecular weights were calculated by ¹H-NMR and by gel permeationchromatography (“GPC”). Absolute molecular weights were obtained byuniversal calibration method using polystyrene and poly(methylmethacrylate) standards. Table 2 shows the characterization of other RMCmonomers synthesized by the triflic acid ring opening polymerization.TABLE 2 Mole % Mole % Mole % Mn Mn Phenyl Methyl Methacrylate (NMR)(GPC) n_(D) A 6.17 87.5 6.32 1001  946 1.44061 B 3.04 90.8 6.16  985 716 1.43188 C 5.26 92.1 2.62 1906 1880 — D 4.16 94.8 1.06 4054 42001.42427 E 0 94.17 5.83  987 1020 1.42272 F 0 98.88 1.12 3661 43001.40843

[0072] At 10-40 wt %, these RMC monomers of molecular weights 1000 to4000 g/mol with 3-6.2 mole % phenyl content are completely miscible,biocompatible, and form optically clear prisms and lenses whenincorporated in the silicone matrix. RMC monomers with high phenylcontent (4-6 mole %) and low molecular weight (1000-4000 g/mol) resultedin increases in refractive index change of 2.5 times and increases inspeeds of diffusion of 3.5 to 5.0-times compared to the RMC monomer usedin Table 1 (dimethylsiloxane-diphenylsiloxane copolymer endcapped withvinyldimethyl silane (“DMDPS”) (3-3.5 mole % diphenyl content, 15500g/mol). These RMC monomers were used to make optical elementscomprising: (a) poly-dimethylsiloxane endcapped withdiacetoxymethylsilane (“PDMS”) (36000 g/mol), (b) dimethylsiloxanemethylphenylsiloxane copolymer that is endcapped with amethacryloxylpropyldimethylsilane group, and (c)2,2-dimethoxy-2-phenylacetophenone (“DMPA”). Note that component (a) isthe monomer that forms the first polymer matrix and components (b) and(c) comprise the refraction modulating composition.

EXAMPLE 3

[0073] Fabrication of Intraocular Lenses (“IOL”)

[0074] An intraocular mold was designed according to well-acceptedstandards. See e.g., U.S. Pat. Nos. 5,762,836; 5,141,678; and 5,213,825.Briefly, the mold is built around two plano-concave surfaces possessingradii of curvatures of −6.46 mm and/or −12.92 mm, respectively. Theresulting lenses are 6.35 mm in diameter and possess a thickness rangingfrom 0.64 mm, 0.98 mm, or 1.32 mm depending upon the combination ofconcave lens surfaces used. Using two different radii of curvatures intheir three possible combinations and assuming a nominal refractiveindex of 1.404 for the IOL composition, lenses with pre-irradiationpowers of 10.51 D (62.09 D in air), 15.75 D (92.44 in air), and 20.95 D(121.46 D in air) were fabricated.

EXAMPLE 4

[0075] Stability of Compositions Against Leaching

[0076] Three IOLs were fabricated with 30 and 10 wt % of RMC monomers Band D incorporated in 60 wt % of the PDMS matrix. After moisture curingof PDMS to form the first polymer matrix, the presence of any free RMCmonomer in the aqueous solution was analyzed as follows. Two out ofthree lenses were irradiated three times for a period of 2 minutes using340 nm light, while the third was not irradiated at all. One of theirradiated lenses was then locked by exposing the entire lens matrix toradiation. All three lenses were mechanically shaken for 3 days in 1.0 MNaCl solution. The NaCl solutions were then extracted by hexane andanalyzed by ¹H-NMR. No peaks due to the RMC monomer were observed in theNMR spectrum. These results suggest that the RMC monomers did not leachout of the matrix into the aqueous phase in all three cases. Earlierstudies on a vinyl endcapped silicone RMC monomer showed similar resultseven after being stored in 1.0 M NaCl solution for more than one year.

EXAMPLE 5

[0077] Toxicological Studies in Rabbit Eyes

[0078] Sterilized, unirradiated and irradiated silicone IOLs (fabricatedas described in Example 3) of the present invention and a sterilizedcommercially available silicone IOL were implanted in albino rabbiteyes. After clinically following the eyes for one week, the rabbits weresacrificed. The extracted eyes were enucleated, placed in formalin andstudied histopathologically. There is no evidence of corneal toxicity,anterior segment inflammation, or other signs of lens toxicity.

EXAMPLE 6

[0079] Irradiation of Silicone Prisms

[0080] Because of the ease of measuring refractive index change (Δn) andpercent net refractive index change (% Δn) of prisms, the inventiveformulations were molded into prisms for irradiation andcharacterization. Prisms were fabricated by mixing and pouring (a) 90-60wt % of high M_(n) PDMS, (b) 10-40 wt % of RMC monomers in Table 2, and(c) 0.75 wt % (with respect to the RMC monomers) of the photoinitiatorDMPA into glass molds in the form of prisms 5 cm long and 8.0 mm on eachside. The silicone composition in the prisms was moisture cured andstored in the dark at room temperature for a period of 7 days to ensurethat the final matrix was non-tacky, clear and transparent.

[0081] Two of the long sides of each prism were covered by a blackbackground while the third was covered by a photomask made of analuminum plate with rectangular windows (2.5 mm×10 mm). Each prism wasexposed to a flux of 1.2 mW/cm² of a collimated 340 nm light (peakabsorption of the photoinitiator) from a 1000 W Xe:Hg arc lamp forvarious time periods. The ANSI guidelines indicate that the maximumpermissible exposure (“MPE”) at the retina using 340 nm light for a10-30000 s exposure is 1000 mJ/cm². Criteria for Exposure of Eye andSkin. American National Standard Z136.1: 31-42 (1993). The single doseintensity 1.2 mW/cm² of 340 nm light for a period of 2 minutescorresponds to 144 mJ/cm² which is well within the ANSI guidelines. Infact, even the overall intensity for three exposures (432 mJ/cm²) iswell within the, ANSI guidelines. FIG. 2 is an illustration of the prismirradiation procedure.

[0082] The prisms were subject to both (i) continuousirradiation—one-time exposure for a known time period, and (ii)“staccato” irradiation—three shorter exposures with long intervalsbetween them. During continuous irradiation, the refractive indexcontrast is dependent on the crosslinking density and the mole % phenylgroups, while in the interrupted irradiation, RMC monomer diffusion andfurther crosslinking also play an important role. During staccatoirradiation, the RMC monomer polymerization depends on the rate ofpropagation during each exposure and the extent of interdiffusion offree RMC monomer during the intervals between exposures. Typical valuesfor the diffusion coefficient of oligomers (similar to the 1000 g/moleRMC monomers used in the practice of the present invention) in asilicone matrix are on the order of 10⁻⁶ to 10⁻⁷ cm²/s. In other words,the inventive RMC monomers require approximately 2.8 to 28 hours todiffuse 1 mm (roughly the half width of the irradiated bands). Thedistance of a typical optical zone in an IOL is about 4 to about 5 mmacross. However, the distance of the optical zone may also be outside ofthis range. After the appropriate exposures, the prisms were irradiatedwithout the photomask (thus exposing the entire matrix) for 6 minutesusing a medium pressure mercury-arc lamp. This polymerized the remainingsilicone RMC monomers and thus “locked” the refractive index of theprism in place. Notably, the combined total irradiation of the localizedexposures and the “lock-in” exposure was still within ANSI guidelines.

EXAMPLE 7

[0083] Prism Dose Response Curves

[0084] Inventive prisms fabricated from RMC monomers described by Table2 were masked and initially exposed for 0.5, 1, 2, 5, and 10 minutesusing 1.2 mW/cm² of the 340 nm line from a 1000 W Xe:Hg arc lamp. Theexposed regions of the prisms were marked, the mask detached and therefractive index changes measured. The refractive index modulation ofthe prisms was measured by observing the deflection of a sheet of laserlight passed through the prism. The difference in deflection of the beampassing through the exposed and unexposed regions was used to quantifythe refractive index change (Δn) and the percentage change in therefractive index (% Δn).

[0085] After three hours, the prisms were remasked with the windowsoverlapping with the previously exposed regions and irradiated for asecond time for 0.5, 1, 2, and 5 minutes (total time thus equaled 1, 2,4, and 10 minutes respectively). The masks were detached and therefractive index changes measured. After another three hours, the prismswere exposed a third time for 0.5, 1, and 2 minutes (total time thusequaled 1.5, 3, and 6 minutes) and the refractive index changes weremeasured. As expected, the % Δn increased with exposure time for eachprism after each exposure resulting in prototypical dose responsecurves. Based upon these results, adequate RMC monomer diffusion appearsto occur in about 3 hours for 1000 g/mole RMC monomer.

[0086] All of the RMC monomers (B-F) except for RMC monomer A resultedin optically clear and transparent prisms before and after theirrespective exposures. For example, the largest % Δn for RMC monomers B,C, and D at 40 wt % incorporation into 60 wt % FPMC were 0.52%, 0.63%and 0.30% respectively which corresponded to 6 minutes of total exposure(three exposures of 2 minutes each separated by 3 hour intervals for RMCmonomer B and 3 days for RMC monomers C and D). However, although itproduced the largest change in refractive index (0.95%), the prismfabricated from RMC monomer A (also at 40 wt % incorporation into 60 wt% FPMC and 6 minutes of total exposure—three exposures of 2 minutes eachseparated by 3 hour intervals) turned somewhat cloudy. Thus, if RMCmonomer A were used to fabricate an IOL, then the RMC must include lessthan 40 wt % of RMC monomer A or the % Δn must be kept below the pointwhere the optical clarity of the material is compromised.

[0087] A comparison between the continuous and staccato irradiation forRMC A and C in the prisms shows that lower % Δn values occurs in prismsexposed to continuous irradiation as compared to those observed usingstaccato irradiations. As indicated by these results, the time intervalbetween exposures (which is related to the amount of RMC diffusion fromthe unexposed to exposed regions) may be exploited to precisely modulatethe refractive index of any material made from the inventive polymercompositions.

[0088] Exposure of the entire, previously irradiated prisms to a mediumpressure Hg arc lamp polymerized any remaining free RMC, effectivelylocking the refractive index contrast. Measurement of the refractiveindex change before and after photolocking indicated no furthermodulation in the refractive index.

EXAMPLE 8

[0089] Optical Characterization of IOLs

[0090] Talbot interferometry and the Ronchi test were used toqualitatively and quantitatively measure any primary optical aberrations(primary spherical, coma, astigmatism, field curvature, and distortion)present in pre- and post-irradiated lenses as well as quantifyingchanges in power upon photopolymerization.

[0091] In Talbot interferometry, the test IOL is positioned between thetwo Ronchi rulings with the second grating placed outside the focus ofthe IOL and rotated at a known angle, θ, with respect to the firstgrating. Superposition of the autoimage of the first Ronchi ruling(p₁=300 lines/inch) onto the second grating (P₂=150 lines/inch) producesmoiré fringes inclined at an angle, α₁. A second moiré fringe pattern isconstructed by axial displacement of the second Ronchi ruling along theoptic axis a known distance, d, from the test lens. Displacement of thesecond grating allows the autoimage of the first Ronchi ruling toincrease in magnification causing the observed moiré fringe pattern torotate to a new angle, α₂. Knowledge of moiré pitch angles permitsdetermination of the focal length of the lens (or inversely its power)through the expression:$f = {\frac{p_{1}}{p_{2}}{{d\left( {\frac{1}{{\tan \quad \alpha_{2}\quad \sin \quad \theta} + {\cos \quad \theta}} - \frac{1}{{\tan \quad \alpha_{1}\quad \sin \quad \theta} + {\cos \quad \theta}}} \right)}^{- 1}.}}$

[0092] To illustrate the applicability of Talbot interferometry to thiswork, moiré fringe patterns of one of the inventive, pre-irradiated IOLs(60 wt % PDMS, 30 wt % RMC monomer B, 10 wt % RMC monomer D, and 0.75%DMPA relative to the two RMC monomers) measured in air is presented inFIG. 3. Each of the moiré fringes was fitted with a least squaresfitting algorithm specifically designed for the processing of moirépatterns. The angle between the two Ronchi rulings was set at 12°, thedisplacement between the second Ronchi ruling between the first andsecond moiré fringe patterns was 4.92 mm, and the pitch angles of themoiré fringes, measured relative to an orthogonal coordinate systemdefined by the optic axis of the instrument and crossing the two Ronchirulings at 90°, were α₁=−33.2°±0.30° and α₂=−52.7°±0.40°. Substitutionof these values into the above equation results in a focal length of10.71±0.50 mm (power=93.77±4.6 D).

[0093] Optical aberrations of the inventive IOLs (from eitherfabrication or from the stimulus-induced polymerization of the RMCcomponents) were monitored using the “Ronchi Test” which involvesremoving the second Ronchi ruling from the Talbot interferometer andobserving the magnified autoimage of the first Ronchi ruling afterpassage though the test IOL. The aberrations of the test lens manifestthemselves by the geometric distortion of the fringe system (produced bythe Ronchi ruling) when viewed in the image plane. A knowledge of thedistorted image reveals the aberration of the lens. In general, theinventive fabricated lenses (both pre and post irradiation treatments)exhibited sharp, parallel, periodic spacing of the interference fringesindicating an absence of the majority of primary-order opticalaberrations, high optical surface quality, homogeneity of n in the bulk,and constant lens power. FIG. 4 is an illustrative example of aRonchigram of an inventive, pre-irradiated IOL that was fabricated from60 wt % PDMS, 30 wt % RMC monomer B, 10 wt % RMC monomer D, and 0.75% ofDMPA relative to the 2 RMC monomers.

[0094] The use of a single Ronchi ruling may also be used to measure thedegree of convergence of a refracted wavefront (i.e., the power). Inthis measurement, the test IOL is placed in contact with the firstRonchi ruling, collimated light is brought incident upon the Ronchiruling, and the lens and the magnified autoimage is projected onto anobservation screen. Magnification of the autoimage enables measurementof the curvature of the refracted wavefront by measuring the spatialfrequency of the projected fringe pattern. These statements arequantified by the following equation:$P_{V} = {\frac{1000}{L}\left( {1 + \frac{d_{s}}{d}} \right)}$

[0095] wherein P_(v) is the power of the lens expressed in diopters, Lis the distance from the lens to the observing plane, d_(s), is themagnified fringe spacing of the first Ronchi ruling, and d is theoriginal grating spacing.

EXAMPLE 9

[0096] Power Changes from Photopolymerization of the Inventive IOLs

[0097] An inventive IOL was fabricated as described by Example 3comprising 60 wt % PDMS (n_(D)=1.404), 30 wt % of RMC monomer B(n_(D)=1.4319), 10 wt % of RMC monomer D (n_(D)=1.4243), and 0.75 wt %of the photoinitiator DMPA relative to the combined weight percents ofthe two RMC monomers. The IOL was fitted with a 1 mm diameter photomaskand exposed to 1.2 mW/cm² of 340 nm collimated light from a 1000 W Xe:Hgarc lamp for two minutes. The irradiated lens was then placed in thedark for three hours to permit polymerization and RMC monomer diffusion.The IOL was photolocked by continuously exposing the entire for sixminutes using the aforementioned light conditions. Measurement of themoiré pitch angles followed by substitution into equation 1 resulted ina power of 95.1±2.9 D (f=10.52±0.32 mm) and 104.1±3.6 D (f=9.61 mm ±0.32mm) for the unirradiated and irradiated zones, respectively.

[0098] The magnitude of the power increase was more than what waspredicted from the prism experiments where a 0.6% increase in therefractive index was routinely achieved. If a similar increase in therefractive index was achieved in the IOL, then the expected change inthe refractive index would be 1.4144 to 1.4229. Using the new refractiveindex (1.4229) in the calculation of the lens power (in air) andassuming the dimensions of the lens did not change uponphotopolymerization, a lens power of 96.71 D (f=10.34 mm) wascalculated. Since this value is less than the observed power of104.1±3.6 D, the additional increase in power must be from anothermechanism.

[0099] Further study of the photopolymerized IOL showed that subsequentRMC monomer diffusion after the initial radiation exposure leads tochanges in the radius of curvature of the lens. See e.g., FIG. 5. TheRMC monomer migration from the unradiated zone into the radiated zonecauses either or both of anterior and posterior surfaces of the lens toswell thus changing the radius of curvature of the lens. It has beendetermined that a 7% decrease in the radius of curvature for bothsurfaces is sufficient to explain the observed increase in lens power.

[0100] The concomitant change in the radius of curvature was furtherstudied. An identical IOL described above was fabricated. A Ronchiinterferogram of the IOL is shown in FIG. 6a (left interferogram). Usinga Talbot interferometer, the focal length of the lens was experimentallydetermined to be 10.52±0.30 mm (95.1 D±2.8 D). The IOL was then fittedwith a 1 mm photomask and irradiated with 1.2 mW/cm² of 340 collimatedlight from a 1000 W Xe:Hg arc lamp continuously for 2.5 minutes. Unlikethe previous IOL, this lens was not “locked in” three hours afterirradiation. FIG. 6b (right interferogram) is the Ronchi interferogramof the lens taken six days after irradiation. The most obvious featurebetween the two interference patterns is the dramatic increase in thefringe spacing, which is indicative of an increase in the refractivepower of the lens.

[0101] Measurement of the fringe spacings indicates an increase ofapproximately +38 diopters in air (f≈7.5 mm). This corresponds to achange in the order of approximately +8.6 diopters in the eye. Sincemost post-operative corrections from cataract surgery are within 2diopters, this experiment indicates that the use of the inventive IOLSwill permit a relatively large therapeutic window.

EXAMPLE 10

[0102] Photopolymerization Studies of Non-Phenyl-Containing IOLs

[0103] Inventive IOLs containing non-phenyl containing RMC monomers werefabricated to further study the swelling from the formation of thesecond polymer matrix. An illustrative example of such an IOL wasfabricated from 60 wt % PDMS, 30 wt % RMC monomer E, 10 wt % RMC monomerF, and 0.75% DMPA relative to the two RMC monomers. The pre-irradiationfocal length of the resulting IOL was 10.76 mm (92.94±2.21 D).

[0104] In this experiment, the light source was a 325 nm laser line froma He:Cd laser. A 1 mm diameter photomask was placed over the lens andexposed to a collimated flux of 0.75 mW/cm² at 325 nm for a period oftwo minutes. The lens was then placed in the dark for three hours.Experimental measurements indicated that the focal length of the IOLchanged from 10.76 mm±0.25 mm (92.94 D±2.21 D) to 8.07 mm±0.74 mm(123.92 D±10.59 D) or a dioptric change of +30.98 D±10.82 D in air. Thiscorresponds to an approximate change of +6.68 D in the eye. The amountof irradiation required to induce these changes is only 0.09 J/cm², avalue well under the ANSI maximum permissible exposure (“MPE”) level of1.0 J/cm².

EXAMPLE 11

[0105] Monitoring for Potential IOL Changes from Ambient Light

[0106] The optical power and quality of the inventive IOLs weremonitored to show that handling and ambient light conditions do notproduce any unwanted changes in lens power. A 1 mm open diameterphotomask was placed over the central region of an inventive IOL(containing 60 wt % PDMS, 30 wt % RMC monomer E, 10 wt % RMC momnomer F,and 0.75 wt % DMPA relative to the two RMC monomers), exposed tocontinuous room light for a period of 96 hours, and the spatialfrequency of the Ronchi patterns as well as the moiré fringe angles weremonitored every 24 hours. Using the method of moiré fringes, the focallength measured in the air of the lens immediately after removal fromthe lens mold is 10.87±0.23 mm (92.00 D±1.98 D) and after 96 hours apfexposure to ambient room light is 10.74 mm±0.25 mm (93.11 D±12.22 D).Thus, within the experimental uncertainty of the measurement, it isshown that ambient light does not induce any unwanted change in power. Acomparison of the resulting Ronchi patterns showed no change in spatialfrequency or quality of the interference pattern, confirming thatexposure to room light does not affect the power or quality of theinventive IOLs.

EXAMPLE 12

[0107] Effect of the Lock in Procedure of an Irradiated IOL

[0108] An inventive IOL whose power had been modulated by irradiationwas tested to see if the lock-in procedure resulted in furthermodification of lens power. An IOL fabricated from 60 wt % PDMS, 30 wt %RMC monomer E, 10 wt % RMC monomer F, and 0.75% DMPA relative to the twoRMC monomers was irradiated for two minutes with 0.75 mW/cm² of the 325nm laser line from a He:Cd laser and was exposed for eight minutes to amedium pressure Hg arc lamp. Comparisons of the Talbot images before andafter the lock in procedure showed that the lens power remainedunchanged. The sharp contrast of the interference fringes indicated thatthe optical quality of the inventive lens also remained unaffected.

[0109] To determine if the lock-procedure was complete, the IOL wasrefitted with a 1 mm diameter photomask and exposed a second time to0.75 mW/cm² of the 325 laser line for two minutes. As before, noobservable change in fringe space or in optical quality of the lens wasobserved.

EXAMPLE 13

[0110] Monitoring for Potential IOL Changes from the Lock-in

[0111] A situation may arise wherein the implanted IOL does not requirepost-operative power modification. in such cases, the IOL must be lockedin so that its characteristic will not be subject to change. Todetermine if the lock-in procedure induces undesired changes in therefractive power of a previously unirradiated IOL, the inventive IOL(containing 60 wt % PDMS, 30 wt % RMC monomer E, 10 wt % RMC monomer F,and 0.75 wt % DMPA relative to the two RMC monomers) was subject tothree 2 minute irradiations over its entire area that was separated by a3 hour interval using 0.75 mW/cm² of the 325 laser line from a He:Cdlaser. Ronchigrams and moiré fringe patterns were taken prior to andafter each subsequent irradiation. The moiré fringe patterns taken ofthe inventive IOL in air immediately after removal from the lens moldand after the third 2 minute irradiation indicate a focal length of10.50 mm±0.39 mm (95.24 D±3.69 D) and 10.12 mm±0.39 mm (93.28 D±3.53D)respectively. These measurements indicate that photolocking a previouslyunexposed lens does not induce unwanted changes in power. In addition,no discernable change in fringe spacing or quality of the Ronchi fringeswas detected indicating that the refractive power had not changed due tothe lock-in.

What is claimed is:
 1. An optical element comprising: a first polymer matrix and a refraction modulating composition dispersed therein wherein the refraction modulating composition is capable of stimulus-induced polymerization.
 2. The optical element as in claim 1 wherein the refraction modulating composition is capable of photo-induced polymerization.
 3. The optical element as in claim 1 wherein the optical element is a prism.
 4. The optical element as in claim 1 wherein the optical element is a lens.
 5. A lens comprising: a first polymer matrix and a refraction modulating composition dispersed therein wherein the refraction modulating composition is capable of photo-induced polymerization.
 6. The lens as in claim 5 wherein the first polymer matrix is selected from the group consisting of poly-acrylate, poly-methacrylate, poly-vinyl, poly-siloxane, and poly-phosphazene.
 7. The lens as in claim 5 wherein the refraction modulating composition includes a component selected from the group consisting of an acrylate, methacrylate, vinyl, siloxane, and phosphazine.
 8. The lens as in claim 5 wherein the refraction modulating composition comprises a monomer of the formula X—Y—X¹ and a photoinitiator wherein Y is

wherein: m and n are each independently an integer and R¹, R², R³, R⁴, and R⁵ are each independently selected from the group consisting hydrogen, alkyl, aryl, and heteroaryl; and Z is a photopolymerizable group.
 9. The lens as in claim 6 wherein the first polymer matrix includes a poly-siloxane.
 10. The lens as in claim 6 wherein the first polymer matrix includes a poly-acrylate.
 11. The lens as in claim 8 wherein R¹, R², R³, R⁴, R⁵, and R⁶ are each independently a C₁-C₁₀ alkyl or phenyl and Z is includes a moiety selected from the group consisting of acrylate, allyloxy, cinnamoyl, methacrylate, cinnamoyl, stibenyl, and vinyl.
 12. The lens as in claim 11 wherein R¹, R², and R³, R⁵, and R⁶ are selected from the group consisting of methyl, ethyl and propyl and R⁴ is phenyl.
 13. The lens as in claim 11 wherein the monomer is (i) dimethylsiloxane-diphenylsiloxane copolymer endcapped with a vinyldimethylsilane group, (ii) dimethylsiloxane-methylphenylsiloxane copolymer endcapped with a methacryloxypropyldimethylsilane group, or (iii) dimethylsiloxane endcapped with a methacryloxypropyldimethylsilane group and the photoinitiator is 2,2-dimethoxy-2-phenylacetophenone.
 14. An intraocular lens comprising: a polysiloxane matrix and a refraction modulating composition dispersed therein wherein the refraction modulating composition is capable of photo-induced polymerization.
 15. The intraocular lens as in claim 14 wherein the polysiloxane matrix is poly-dimethyl siloxane endcapped with diacetoxymethylsilane.
 16. The intraocular lens as in claim 14 wherein the refraction modulating composition comprises: dimethylsiloxane-diphenylsiloxane copolymer endcapped with a vinyldimethylsilane group; dimethylsiloxane-methylphenylsiloxane copolymer endcapped with a methacryloxypropyldimethylsilane group; or dimethylsiloxane endcapped with a methacryloxypropyldimethylsilane group; and, 2,2-dimethoxy-2-phenylacetophenone.
 17. A method of implementing an optical element having a refractive modulating composition dispersed therein, comprising: (a) exposing at least a portion of the optical element to a stimulus whereby the stimulus induces the polymerization of the refraction modulating composition.
 18. The method as in claim 17 wherein the optical element is a prism or a lens.
 19. The method as in claim 17 wherein the exposed portion represents the entire optical element.
 20. The method as in claim 17 further comprising (b) waiting an interval of time; and (c) re-exposing the portion of the optical element to the stimulus to induce the further polymerization of the refraction modulating composition within said portion.
 21. The method as in claim 20 further comprising repeating steps (b) and (c).
 22. The method as in claim 20 further comprising: exposing the entire optical element to the stimulus.
 23. A method of implementing an intraocular lens having a refractive modulating composition dispersed therein and implanted within the eye, comprising: (a) exposing at least a portion of the lens to a light source whereby the light source induces the polymerization of the refraction modulating composition.
 24. The method as in claim 23 wherein the exposed portion represents the entire intraocular lens.
 25. The method as in claim 23 further comprising: (b) waiting an interval of time; and (c) re-exposing the portion of the lens to the light source to induce the further polymerization of the refraction modulating composition within said portion.
 26. The method as in claim 23 further comprising repeating steps (b) and (c).
 27. The method as in claim 23 further comprising: exposing the entire lens to the light source.
 28. The method as in claim 23 wherein the exposed portion is the optical zone of the lens.
 29. The method as in claim 23 wherein the exposed portion is the outer rim of the lens.
 30. The method as in claim 23 wherein the exposed portion is along a meridian of the lens.
 31. A method of implementing an intraocular lens having a refractive modulating composition dispersed therein and implanted within the eye, comprising: (a) exposing a first portion of the lens to a light source whereby the light source induces the polymerization of the refraction modulating composition and (b) exposing a second portion of the lens to the light source.
 32. The method as in claim 31 further comprising exposing a third portion of the lens to a light source.
 33. The method as in claim 31 further comprising exposing the entire lens to the light source.
 34. A method for fabricating an optical element, comprising: mixing a first polymer matrix composition with a refraction modulating composition to form a reaction mixture; placing the reaction mixture into a mold; polymerizing the first polymer matrix composition to form a first polymer matrix with the refraction modulating composition dispersed therein; and, removing said optical element from the mold.
 35. A method for making an optical element comprising: a) preparing a mixture of a first polymer matrix composition, and a refraction modulating composition; b) polymerizing said first polymer matrix composition to form a first polymer matrix having the refraction modulating composition dispersed throughout the first polymer matrix.
 36. The method of claim 35 wherein said first polymer matrix composition comprises monomer selected from the group consisting of acrylates, methacrylates, phosphazenes, siloxanes and vinyls.
 37. The method of claim 35 wherein said refraction modulating composition is photopolymerizable.
 38. The method of claim 35 wherein the further mixture comprising a photoinitiator
 39. The method of claim 35 further comprising the step of placing the mixture of step a) into a mold before the polymerization step b).
 40. The method of claim 39 further comprising the step of removing the optical element from the mold after the polymerization step b).
 41. The method of claim 35 wherein said refraction modulation composition has the formula X—Y—X¹ wherein X and X¹ independently comprise a terminal siloxane moiety with a group capable of stimulus induced polymerization and Y is a siloxane moiety having the formula.

wherein m and n are integers and R¹, R², R³ and R⁴ are independently selected from the group consisting of hydrogen, alkyl, aryl and heteroaryl.
 42. The method of claim 35 wherein said optical element is an intraocular lens.
 43. The method of claim 35 wherein said optical element is a contact lens.
 44. The method of claim 35 wherein said optical element is a prism.
 45. The method of claim 35 wherein said optical element is a data storage device.
 46. The method of claim 35 further comprising the step of exposing the optical element to an external stimulus to cause a change in the optical element.
 47. The method of claim 46 wherein said external stimulus is electromagnetic radiation.
 48. The method of claim 47 wherein the light induces the polymerization of the refraction modulating composition thereby causing the change in the optical element.
 49. The method of claim 46 wherein said change is a change in the shape of the optical element.
 50. The method of claim 46 wherein said change is a change in the refractive index of the optical element.
 51. The method of claim 46 wherein the change is a change in both the shape and refractive index of the optical element.
 52. The method of claim 48 wherein the change is a change in the shape of the optical element.
 53. The method of claim 48 wherein the change is a change in the refractive index of the optical element.
 54. The method of claim 48 wherein the change is a change in both the shape and refractive index of the optical element.
 55. A method for fabricating optical element comprising a) preparing a mixture of first polymer matrix composition and refraction modulating composition; b) polymerizing the first polymer matrix composition to form a first polymer matrix; c) polymerizing the refraction modulating composition to form a second polymer matrix within at least a portion of said optical element.
 56. The method of claim 55 wherein the polymerization of the refraction modulating composition causes changes in the refractive properties of the optical element.
 57. The method of claim 55 wherein the polymerization of said refractive modulating composition causes a change in the shape of the optical element.
 58. The method of claim 55 wherein the polymerization of the refraction modulating composition is photopolymerization.
 59. The method of claim 55 wherein the polymerization of the first polymer matrix composition is preformed in vitro.
 60. The method of claim 55 wherein said mixture further comprises a photo initiator.
 61. The method of claim 55 wherein the polymerization of the refraction modulating composition is performed in vivo.
 62. The method of claim 55 wherein said refraction modulation composition has the formula X—Y—X¹ wherein X and X¹ independently comprise a terminal siloxane moiety with a group capable of stimulus induced polymerization and Y is a siloxane moiety having the formula:

wherein m and n are integers and R¹, R², R³ and R⁴ are independently selected from the group consisting of hydrogen, alkyl, aryl and heteroaryl.
 63. The method of claim 62 wherein X and X¹ have the formula

wherein R⁵ and R⁶ are independently selected from the group consisting of hydrogen, alkyl, aryl and hetero alkyl and Z contains a photopolymerizable group.
 64. The method of claim 63 wherein R¹, R², R³, R⁵ and R⁶ are alkyls and R⁴ is aryl.
 65. The method of claim 63 wherein R¹, R², R³, R⁵ and R⁶ are alkyls and R³ and R⁴ are aryl.
 66. The method of claim 55 wherein said optical element is an intraocular lens.
 67. The method of claim 55 wherein said optical element is a contact lens.
 68. The method of claim 55 wherein said optical element is a prism.
 69. The method of claim 55 wherein said optical element is a data storage device. 